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CAIE IGCSE Physics Wave Speed Calculations

Practise applying v = fλ to water, sound, electromagnetic and seismic waves, with equation rearrangement and careful prefix and length conversion.

Syllabus
2026–2028
Course
Physics 0625

Exam points

  • rearrange v = fλ for speed, frequency or wavelength before substituting values
  • convert GHz, MHz, kHz, kilometres, centimetres or millimetres into consistent units
  • use the correct medium-specific speed, including 3.0 × 10⁸ m/s for electromagnetic waves

3.1.4—Recall/use: for wave speed v = f λ question 1

[Maximum number: 3]

A ray of light is incident on a soap film. Fig. 5.1 shows a magnified image of a small part of the soap film. The ray of light is refracted as it enters the soap film.

Figure for Question 3.1.4—Recall/use: for wave speed v = f λ question 1 — CAIE IGCSE Physics

soap film
```
air
```


The refractive index of the soap film is 1.28 .

The ray of light is monochromatic red light with a wavelength of 680 nm in air.

Calculate the frequency of the light.

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